Breath, body, words (#2)

The vocabulary of anatomy features unexpected synonyms. The word 'alveolus' is Latin for a small cavity or indentation. The anatomy of the body features many such cavities. So it is perhaps unsurprising that anatomists pull the word into service in two different ways. First in the description of the hundreds of millions of tiny sacs of blood contained in the lungs. Second in the description of the 32 or so sockets in the gums that hold the teeth. These are, respectively, the pulmonary alveoli and the dental alveoli.

A sketch from the text.

Spherical cavities of the lungs, the pulmonary alveoli measure in microns and number in the hundreds of millions. Sheathed in epithelia and a coating of capillaries, it is along the membranes of these tiny spaces that both the breath and blood must pass. The dental alveoli are the sockets of the teeth; in adults, they number just thirty-two. Gomphoses are fibrous joints that move almost not at all and through which both rows of teeth bind to the sockets that contain them. Absent some singular moment of violence — a sudden fall, a blow to the face — the alveoli of the teeth stand fixed for a lifetime in their task. Small cavities interior to the lungs, small cavities in which to house the teeth. Small cavities connected the each to the other in only the passing of the breath.

The last sentence focuses on the breath. The last sentence imagines the breath as a type of invisible tissue that connects the many millions of alveoli in the lungs with the far fewer alveoli in the gums.

The pulmonary alveoli and the dental alveoli share nothing much in common except a name. But when thinking deeply into the structure of the body, it is possible to imagine these different things — these different classes of cavity — as connecting not only in name but in body.